Hardwiring one Wifi point by itself is not recommended. Setups where you have some of your Wifi points hardwired and some not are much more likely to cause problems that are very hard to diagnose. The primary one being that if one of your non-hardwired Wifi points can establish even a weak connection back to your primary Wifi point it will do that, over connecting to an intermediate closer Wifi point, because it prefers the least hops to get back to the primary Wifi point. This is also the reason Google recommends placing your primary Wifi point as close as possible to the centre of your home. The best advice I can give you is to do one or the other, not both. Either build a pure mesh topology (i.e. don't hardwire any of the points via ethernet) and follow Google's placement guidelines, which it sounds like you're at at the limits of from what you said, or, build a full ethernet backhaul setup where all your Wi-Fi points are hardwired.
Hardwire Nest Wifi Pro, Nest Wifi or Google Wifi with Ethernet - Google Nest Help
